What if left and right politics is a precursor to human speciation?

1) Again depends on the culture which is often unpredictable due to their complexity, but one possible avenue includes exclusion and non-acceptance in that society, citing a lack of "unity" within that particular polarity (which is of course ironic). They could face hardships intended to help propel the loser back into competition through anger and striving to be seen as worthy. If the culture is more on the efficient end, then the loser may simply face death or extreme labor for the underbelly of the polarity's momentum.

2) Surprisingly a similar result may occur in the second society, but this highly depends upon how well developed those of that society are on the inside. If not so well developed, the living hell scenario, then such people could "disappear" and be killed or be forcibly "reeducated" ala 1984. If well developed however, the punishment could be met with much more empathy, the individual being guided in directions to understand his supposed mistake whether at first by consulship by others, then to formal education which then become more severe if the individual continues to pose a threat to that system. Another possibility is exile, simply ejecting the individual from the community to have them live on their own. This can also have varying degrees of implementation.

Population wise, #1 would strive to outdo each other. #2 would be concerned about the overall sustainability vis a vis the supplies readily available, as a general rule of thumb.

@CoxswainOtter The culture in the main and whether inner development is seen as the primary foundation for an "advanced" society. Whether their actions are seen for what they are with full understanding by others or if they are seen by others as confusion for not knowing themselves. All this depends on who starts said society and how developed they are as that sets the pace. The method used depends on the starting level, so lower it would be more of a religious understanding to enforce servitude to a higher "good" which has a chance of corruption due to human nature. This can have brutal enforcement as a result. However, if the population already sees their mistakes as inner imperfections than the discipline needed would be far lessened as each would understand they all hold some level of responsibility. The spectrum of understanding for this is quite wide and infinitely varied and so this is just a generalization.

In short, the lower end requires an artificial measuring mechanism used for troublemakers due to the lack of understanding how to handle the situation themselves, and the higher end assumes more responsibility as others actions show one's inner development and this is understood by the society. They then can see how well the one in the wrong knows themselves and his/her reality before them and all work to coalesce to open doors that each is good at showing said individual.

@CoxswainOtter Only if such understandings was largely common amongst the population. At that point the understanding of unity would be commonplace such that all are but reflections of the self propelling one to remedy the situation, but that's much higher up.